8H35/40

Common issues

• Cylinder Cover wear and surface corrosion, particularly in marine environments, requiring regular reconditioning during overhauls.
• Fuel injector nozzle clogging or wear due to HFO operation and high-pressure common rail system, leading to poor combustion and increased exhaust temperatures.
• Exhaust valve burning or seat wear, often exacerbated by HFO impurities and high thermal loads.
• Piston ring wear, scuffing, or breakage, resulting in increased blow-by, lube oil consumption, and potential liner damage.
• Turbocharger bearing wear or fouling of compressor/turbine blades, impacting engine efficiency and power output.
• Main and connecting rod bearing wear, especially if lube oil quality or filtration is compromised.
• Common Rail fuel pump or pressure accumulator issues, affecting fuel delivery consistency and engine performance.
• Cooling water system leaks or internal corrosion, potentially leading to localized overheating or component failure.

Inspection checklist

• Review engine logbook entries for running hours, load profiles, alarm history, and fuel/lube oil consumption trends.
• Conduct visual inspection for any leaks (fuel, lube oil, cooling water, exhaust gas) around the engine block, piping, and components.
• Check exhaust gas temperatures per cylinder for uniformity; significant deviations indicate combustion issues (injectors, valves, compression).
• Verify proper operation and calibration of safety devices: overspeed trip, low lube oil pressure shutdown, high cooling water temperature shutdown.
• Inspect turbocharger for abnormal noise, excessive axial/radial play, and cleanliness of compressor/turbine sides.
• Perform crankcase inspection (if accessible or during planned maintenance) for abnormal wear debris, water ingress, or oil mist detector alarm history.
• Check fuel system integrity, including common rail pressure stability (if monitoring available), filter condition, and high-pressure pipe connections.
• Assess engine foundation bolts for tightness and signs of movement, and inspect engine mounting for excessive vibration.
• Review latest lube oil analysis reports for wear metals, TBN, viscosity, and water content, especially for main and connecting rod bearings.

Service intervals

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Complete Fuel Injector unit (at least one per cylinder type)
• Exhaust Valve Spindle and Seat (at least one set)
• Full set of Piston Rings for at least one cylinder
• Cylinder Head Gasket (at least one)
• Main and Connecting Rod Bearing Shells (one set each)
• Fuel Filter Elements (primary and secondary)
• Lube Oil Filter Elements
• Turbocharger Bearing Cartridge or repair kit

Safety

• High-pressure fuel leaks from the Common Rail system, posing severe fire and injury risks. Ensure proper shielding and immediate attention to any leaks.
• Potential for crankcase explosions due to oil mist accumulation. Verify proper functioning and calibration of the oil mist detector.
• Integrity of exhaust gas piping insulation and lagging to prevent burns and fire hazards from hot surfaces.
• Safe working procedures around rotating machinery (flywheel, coupling, turbocharger) during engine operation or maintenance.
• Starting air system safety, including proper operation of relief valves, bursting discs, and non-return valves to prevent overpressure or backfire.

Class survey

A class surveyor will typically focus on verifying the engine's compliance with statutory and classification rules. This includes a thorough review of engine logbooks, maintenance records, lube oil analysis reports, and indicator diagrams. Key checks involve testing of all safety devices (overspeed, low LO pressure, high CW temp), visual inspection of the engine's overall condition, foundation bolts, exhaust system integrity, and fuel oil system for leaks or fire hazards. If the engine is opened for maintenance, the surveyor will inspect internal components such as cylinder liners, pistons, bearings, and valves for wear and condition. The starting air system, including relief valves and non-return valves, will also be checked for proper function and certification. Emphasis will be placed on the Common Rail system's integrity and any modifications.